Reason I ask is, a while ago I was parked on a moon which the game said had a rotational period of over 3 days, it was just after sunset and too dark to take some screenies, so I decided to wait a bit. Logged on again about six hours later and it was sunrise already. Conversely, I'm currently in orbit on the dark side of a planet which the game says has a rotational period of 1.1d, I've been checking every few hours for nearly a full (realtime) day now and still hovering in the midnight shade.